Abstract : How do design teams think in order to bring about breakthrough concepts? What are the main underlying cognitive mechanisms at the front end of such creation processes? Empirical evidence shows that firms often have difficulties breaking free from the conventional ideas surrounding products. Although prior works in creativity emphasize the ideation process in the design teams, little theoretical attention has been devoted to understand these teams' approaches to think about new ideas. Through the experimental analysis of ten design teams aiming to elaborate upon a breakthrough concept of a movable and eco-friendly Antarctica museum, we examine the thought processes used to follow or go beyond the existing museums. This research suggests that thinking outside the box does not follow the two-steps funnel model in which idea generation is separated from selection. Our results better support a process where breakthrough concepts result from the continuous reconfiguration of known properties and unknown properties. Our findings indicate that elaborating a breakthrough concept toward an "ecosystem of properties" approach (i.e. connected network of solutions) outperforms the "primer concept fixation" (i.e. attachment to first solutions) and "random exploration" approaches (i.e. free generation of many isolated solutions). Managerial recommendations to assist design teams in pursuing an "ecosystem of properties" approach are provided.